If I used Steelix's "Gigaton Shake" on my previous turn, would Channeler allow my Pokemon to attack this turn?
Yes, the effect of Gigaton Shake would be removed, and your Pokemon would be able to attack.
Source: Unified Minds FAQ (2019-07-19), TPCi Rules Team (2019-08-01)
Can I use Giant Hearth if I have no cards left in my deck, and just discard a card from my hand?
Yes, you can. The first sentence of Giant Hearth says to discard a card from your hand. Then if you can do that, you do as much of the rest of the card as you can, which in this case is draw no cards.
Source: TPCi Rules Team (2019-08-01)
If I have Focus Sash attached to Marshadow & Machamp GX and then use its "Acme of Heroism GX" attack, which one takes precedence if Marshadow & Machamp GX would be KO'd by damage from an opponent's attack?
You would choose, as they have the same effect, you choose the order of resolution.
Source: TPCi Rules Team (2019-06-27)
If I use Raichu's "Evoshock" Ability to paralyze my opponent's Active Pokemon, does the Paralyzed status condition get removed if my opponent attaches a Stealthy Hood to that Pokemon on their next turn?
The Evoshock Ability's effect is to Paralyze the opponent's Pokemon; once that Special Condition has been placed it is no longer considered an effect of the Ability at the time your opponent attaches the Stealthy Hood. Therefore, your opponent's Pokemon remains Paralyzed.
Source: TPCi Rules Team (2019-06-06)
Can you play Darkrai GX with "Restoration" Ability from your Discard Pile if Power Plant is in play? And if so, do you do all of its effects?
Since the Discard Pile is not considered "in play", Darkrai GX can use its Restoration Ability to put it onto the Bench and attach a Darkness Energy card from the Discard Pile to it. Once all of the Ability's effects are complete, then Power Plant shuts off the Ability.
Source: TPCi Rules Team (2019-06-06)
Can a Pokemon with an attack that does damage to the opponent's Bench get through Mr. Mime's "Bench Barrier" Ability if the Attacking Pokemon has Stealthy Hood attached?
No, it does not get through. The Bench Barrier Ability is not "being done" to the Attacking Pokemon.
Source: TPCi Rules Team (2019-05-30)
Can I use Lycanroc-GX's "Bloodthirsty Eyes to target an opponent's Pokemon with Stealthy Hood attached?
Bloodthirsty Eyes can target a Benched Pokemon with Stealthy Hood attached, but its effect would be immediately blocked. However, if the Pokemon with Stealthy Hood is Active, Bloodthirsty Eyes can target a Benched Pokemon without a Stealthy Hood and the switch would take place.
Source: TPCi Rules Team (2019-05-30)
Does Martial Arts Dojo stadium's +40 more damage apply to Benched Pokemon?
Although the secondary effect is missing the "to the opponent's Active Pokemon" phrase, the intent is for the +40 more damage to only apply to the opponent's Active Pokemon.
Source: TPCi Rules Team (2019-05-09)
If I play Lt. Surge's Strategy first, can I then play a second (or third) Lt. Surge's Strategy to play more than 3 Supporters?
Nope, that doesn't work. The second Lt. Surge's Strategy does not add to the number of additional Supporter cards you can play, so you can't play the second one at all because you cannot play Trainer cards for no effect.
Source: Unbroken Bonds FAQ (2019-04-19), TPCi Rules Team (2019-05-09)
If I have Miltank with the "Moomoo Malt" Ability as my Active Pokemon and I use Welder to attach 2 Fire Energy cards to a Benched Pokemon, does it heal 90 or 180 damage?
Any energies attached from the hand would trigger Moomoo Malt, once for each energy card being attached. So in this case you would heal 180 damage.
Source: TPCi Rules Team (2019-05-09)